jQuery UI dialog插件出错信息:$(this).dialog is not a function

使用jQuery UI 1.7.2 dialog插件，遇到这样的错误：

[img]http://dl.iteye.com/upload/attachment/308166/97c428e4-2ce2-367e-b4df-4c4da7686b95.bmp" alt="" width="210" height="44[/img]

    $("#dialog").dialog({  
         480,  
        height:"auto",  
        resizable: false,  
        draggable: true,  
        modal: true,  
        position: "center",  
        autoOpen: false,  
        dialogClass: "dialog",  
        buttons: {"关闭":function(){  
        $(this).dialog("close");  
        }}  
    });  
      
    $("#chglogpwd").bind("click",function(){  
        $("#dialog").dialog("option","height","400");  
        showModalDialog("#dialog","/accoun/acc/change_logpwd_fm.html?"+new Date().getTime(),"修改登录密码");  
                });  
      
    function showModalDialog(dialogEl,url,title,callback){  
        var $this = $(dialogEl);  
        $this.html("");  
        $this.dialog("option","title",title);  
        $this.dialog("open");  
        $this.load(url).removeClass("hideh");  
    } 

调试了很久，发现在当前页面上加载了jquery的js资源，在被load的那个页面中也加载了jquery的资源。 
<script type="text/javascript" src="/common/js/jquery-1.4.2.min.js"></script> 
尝试将被load的页面中的jquery资源去除，错误便消除。

经测试：asp.net mvc 1.0/2.0不会出现此错误，但是mvc 3.0中就会出现此错误